Struct tracing_subscriber::registry::Registry
source · [−]pub struct Registry { /* private fields */ }
Expand description
A shared, reusable store for spans.
A Registry
is a Subscriber
around which multiple Layer
s
implementing various behaviors may be added. Unlike other types
implementing Subscriber
, Registry
does not actually record traces itself:
instead, it collects and stores span data that is exposed to any Layer
s
wrapping it through implementations of the LookupSpan
trait.
The Registry
is responsible for storing span metadata, recording
relationships between spans, and tracking which spans are active and which
are closed. In addition, it provides a mechanism for Layer
s to store
user-defined per-span data, called extensions, in the registry. This
allows Layer
-specific data to benefit from the Registry
’s
high-performance concurrent storage.
This registry is implemented using a lock-free sharded slab, and is highly optimized for concurrent access.
Span ID Generation
Span IDs are not globally unique, but the registry ensures that no two currently active spans have the same ID within a process.
One of the primary responsibilities of the registry is to generate span
IDs. Therefore, it’s important for other code that interacts with the
registry, such as Layer
s, to understand the guarantees of the
span IDs that are generated.
The registry’s span IDs are guaranteed to be unique at a given point in time. This means that an active span will never be assigned the same ID as another currently active span. However, the registry will eventually reuse the IDs of closed spans, although an ID will never be reassigned immediately after a span has closed.
Spans are not considered closed by the Registry
until every
Span
reference with that ID has been dropped.
Thus: span IDs generated by the registry should be considered unique only at a given point in time, and only relative to other spans generated by the same process. Two spans with the same ID will not exist in the same process concurrently. However, if historical span data is being stored, the same ID may occur for multiple spans times in that data. If spans must be uniquely identified in historical data, the user code storing this data must assign its own unique identifiers to those spans. A counter is generally sufficient for this.
Similarly, span IDs generated by the registry are not unique outside of
a given process. Distributed tracing systems may require identifiers
that are unique across multiple processes on multiple machines (for
example, OpenTelemetry’s SpanId
s and TraceId
s). tracing
span
IDs generated by the registry should not be used for this purpose.
Instead, code which integrates with a distributed tracing system should
generate and propagate its own IDs according to the rules specified by
the distributed tracing system. These IDs can be associated with
tracing
spans using fields and/or stored span data.
Trait Implementations
sourceimpl<'a> LookupSpan<'a> for Registry
impl<'a> LookupSpan<'a> for Registry
sourcefn register_filter(&mut self) -> FilterId
fn register_filter(&mut self) -> FilterId
Registers a Filter
for per-layer filtering with this
Subscriber
. Read more
sourceimpl Subscriber for Registry
impl Subscriber for Registry
sourcefn record(&self, _: &Id, _: &Record<'_>)
fn record(&self, _: &Id, _: &Record<'_>)
This is intentionally not implemented, as recording fields on a span is the responsibility of layers atop of this registry.
sourcefn event(&self, _: &Event<'_>)
fn event(&self, _: &Event<'_>)
This is intentionally not implemented, as recording events is the responsibility of layers atop of this registry.
sourcefn try_close(&self, id: Id) -> bool
fn try_close(&self, id: Id) -> bool
Decrements the reference count of the span with the given id
, and
removes the span if it is zero.
The allocated span slot will be reused when a new span is created.
sourcefn register_callsite(&self, _: &'static Metadata<'static>) -> Interest
fn register_callsite(&self, _: &'static Metadata<'static>) -> Interest
Registers a new callsite with this subscriber, returning whether or not the subscriber is interested in being notified about the callsite. Read more
sourcefn new_span(&self, attrs: &Attributes<'_>) -> Id
fn new_span(&self, attrs: &Attributes<'_>) -> Id
sourcefn record_follows_from(&self, _span: &Id, _follows: &Id)
fn record_follows_from(&self, _span: &Id, _follows: &Id)
Adds an indication that span
follows from the span with the id
follows
. Read more
sourcefn clone_span(&self, id: &Id) -> Id
fn clone_span(&self, id: &Id) -> Id
sourcefn current_span(&self) -> Current
fn current_span(&self) -> Current
Returns a type representing this subscriber’s view of the current span. Read more
sourcefn max_level_hint(&self) -> Option<LevelFilter>
fn max_level_hint(&self) -> Option<LevelFilter>
Returns the highest verbosity level that this Subscriber
will
enable, or None
, if the subscriber does not implement level-based
filtering or chooses not to implement this method. Read more
Auto Trait Implementations
impl RefUnwindSafe for Registry
impl Send for Registry
impl Sync for Registry
impl Unpin for Registry
impl !UnwindSafe for Registry
Blanket Implementations
sourceimpl<T> BorrowMut<T> for T where
T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
const: unstable · sourcefn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
sourceimpl<S> SubscriberExt for S where
S: Subscriber,
impl<S> SubscriberExt for S where
S: Subscriber,
sourceimpl<T> SubscriberInitExt for T where
T: Into<Dispatch>,
impl<T> SubscriberInitExt for T where
T: Into<Dispatch>,
sourcefn set_default(self) -> DefaultGuard
fn set_default(self) -> DefaultGuard
Sets self
as the default subscriber in the current scope, returning a
guard that will unset it when dropped. Read more
sourcefn try_init(self) -> Result<(), TryInitError>
fn try_init(self) -> Result<(), TryInitError>
Attempts to set self
as the global default subscriber in the current
scope, returning an error if one is already set. Read more
sourcefn init(self)
fn init(self)
Attempts to set self
as the global default subscriber in the current
scope, panicking if this fails. Read more